New nucleoside and nucleotide analogs will be prepared and studies as antiviral and antitumor agents. These compounds will include (1) lipophilic phosphates of allenols derived from nucleic acid bases capable of penetrating the cell membrane (2) nucleoside analogues containing cyclopropane or cyclobutane moiety and (3) analogues of the anti-HIV agent carbovir. Antitumor activity will be studies in vitro and in vivo using murine leukemia L1210 cultures and a number of other tumor systems including solid tumors. Antiviral effects will be investigated in assays with human immunodeficiency virus (HIV), hepatitis B virus (HBV), human cytomegalovirus (HCMV), and herpes simplex 1 virus (HSV-1). Mechanisms of action will be studied with the active analogues. Adenine will be tested as substrates for adenosine deaminase.